Valve

ABSTRACT

The valve plug has an axially tapering peripheral wall with a groove therein. An O-ring is disposed in the groove and extends radially outwardly beyond the peripheral wall. The body has an annular seating wall which tapers in the same direction as the plug. In the closed position, the O-ring is compressed between the seating wall and plug sufficiently to provide a tight seal while constraining the wall of the plug and the seating wall from seating engagement so that precise finish of the walls is unnecessary. The plug is supported for axial movement toward and away from the seating wall and for floating slightly radially so that precise fitting and alignment of the plug and seating wall are unnecessary for effective closure. The valve is adjustable to change the rate of flow and delivered pressure by exterior manipulation of the body, or by adjustment means within the body. A resilient coating of TEFLON or silicone is provided on the walls. The plug may be radially expansible by the pressure of fluid at its larger end.

Ute y States Paiet [1 1 Hengesbach 51 Sept. 4, 1973 VALVE [76] Inventor:Robert W. Hengesbach, 7886 [52] US. Cl 137/540, 137/541, 137/542,137/543.13 51 Int. Cl. Fl6k 15/02 [58] Field of Search 137/541, 540,542, 137/543, 543.13, 543.23, 516.27

[56] References Cited UNITED STATES PATENTS 1,776,060 9/1930 Beckwith137/516.27 1,860,004 5/1932 Yardley l37/543.13 2,408,541 10/1946 Wilson251/332 X 2,744,727 5/1956 Osburn 137/543 X 2,965,309 12/1960 Parrott239/426 X 3,152,607 10/1964 Lundeen.... 137/542 X 3,209,777 10/1965Salisbury l37/543.l3 X 3,473,561 10/1969 Svenson et al 137/541 X3,556,136 l/1971 White 251/368 X 3,587,632 6/1971 Clay 137/543 FOREIGNPATENTS OR APPLICATIONS 1,179,894 12/1958 France 137/541 1,228,1913/1960 France l37/543.15

1,500,026 5/1969 Germany 137/542 Primary Examiner-William R. ClineAttorney-John Harrow Leonard [5 7] ABSTRACT I The valve plug has .anaxially tapering peripheral wall with a groove therein. An O-ring isdisposed in the groove and extends radially outwardly beyond theperipheral wall. The body has an annular seating wall which tapers inthe same direction as the plug. in the closed position, the O-ring iscompressed between the seating wall and plug sufficiently to provide atight seal while constraining the wall of the plug and the seating wallfrom seating engagement so that precise finish of the walls isunnecessary. The plug is supported for axial movement toward and awayfrom the seating wall and for floating slightly radially so that precisefitting and alignment of the plug and seating wall are unnecessary foreffective closure.

The valve is adjustable to change the rate of flow and deliveredpressure by exterior manipulation of the body, or by adjustment meanswithin the body.

A resilient coating of TEFLON or silicone is provided on the walls. Theplug may be radially expansible by the pressure of fluid at its largerend.

13 Claims, 11 Drawing Figures VALVE Y BACKGROUND OF INVENTION 1. Fieldof Invention Valve with an axially movable plug adapted for use as acheck valve, flow control valve, and pressure regulating valve.

2. Description of Prior Art Prior valves, such as check valves and thelike, have been provided in which the plug and seat are frustoconical.The seating surfaces thereof are ground and lapped to 'a precise fit anddirectly engage to effect a seal. These valves must be preciselymachined and assembled in order that the plug can be guided so as tomove in direct coaxial alignment with the seat. The plug is constrainedat all times to coaxial relation with the seat so as to prevent anyshifting of the valve plug out of coaxial relation with the seat and anytilting or rocking of the plug transversely of its axis relative to theaxis of the seat. This is to assure precise seating not only forsealing, but also to prevent damage and unequally distributed wear ofthe metal seating surfaces.

These prior valves are not adjustable as to delivered pressure and flow.They are open to the objection that the manufacturing cost is extremelyhigh, and that any accumulation of foreign matter on the seating areasand wear on the guiding parts result in malfunctioning and leakage. Insome instances, a conventional seal is provided on the plug tosupplement or augment the sealing effect of the complementary metalseating surfaces of the plug and seating wall. In these cases, also, thevalve is precisely guided, and sealing depends primarily upon theengagement of the complementary metal seating surfaces. 7

A later development is one in which an O-ring is carried by the plug andis movable axially relative thereto. The plug and seating wall in thebody are metal and are arranged to interengage in seating relation toarrest the forward movement of the plug. Before this seatingoccurs,.however, the O-ring is moved along the plug to a sealingposition with respect to the seating wall. The direct contact of theplug and seating wall prevents squeezing of the O-ring past the plug.Aalve of the lattertype is disclosed In US. Pat. No. 2,912,000, issuedNov. 10, 1959.

The present valveeliminates the necessity for precise guiding of theplug and seating of complementary metal seating surfaces. The valve isgenerally self-cleaning. It is capable of providing an effective sealeven when the seating area of the seat has become fouled with foreignmatter. The valve lends itself to economic quantity production in anyand all sizes desired. It is adjustable as to rate of flow and deliveredpressure.

Various other objects and advantages will become apparent from thefollowing description in which reference is made to the drawing.

SUMMARY OF INVENTION A valve which provides a tight seal without directcontact between the metal plug and seat, is selfcleaning, and issettable for flow and pressure control, each by manipulation of exteriorportions of the valve body.

DESCRIPTION OF DRAWING FIG. 1 is a side elevation of avalve embodyingthe principles of the present invention, the valve being in openposition and part thereof being shown in section for clearness inillustration;

FIG. 2 is a view similar to FIG. 1, but showing the valve. in closedposition;

FIG. 3 is an enlarged fragmentary longitudinal sectional view of thevalve in the open position illustrated in FIG. 1;

FIG. 4 is an enlarged longitudinal sectional view of the valve in theclosed position illustrated in FIG 2;

FIG. 5 is a fragmentary sectional view of the valve and is taken on theline 5--5'in FIG 3;

FIG. 6 is a fragmentary sectional view of the valve and is taken on theline 6-6 of FIG. 3;

FIG. 7 is a view, similar to FIG. 1, illustrating a modified form of thevalve;

FIG. 8 is a fragmentary side elevation of a modified form of the plugused in the valve;

FIG. 9 is a cross sectional view of the modified form of the plug, andis taken on the line 9-9 in FIG. 8;

FIG. 10 is a side elevation, partly in section, illustrating theembodiment of the plug in a water control nozzle; and

FIG. 11 is the side elevation of the modified form of O-ring that may beused in the present invention.

Referring to the drawings, the valve comprises a body 1 composed of aninlet part 2 and a discharge part 3. The parts 2 and 3 are connectedtogether in coaxial telescopic relation for adjustment to differentrelative positions axially by means of external threads 4 on the bodypart 2, and internal threads 5 in the body part 3. The inlet end 6 ofthe part 2 is externally threaded for connection to a source of fluidunder pressure, and the outlet 7 of the part 3 is externally threadedfor connection to a discharge line. The body parts 2 and 3 can besecured firmly in selected axially adjusted positions by means of a lockor jam nut 8, an O-ring 9 being secured between the body parts forproviding a seal in all adjusted positions of the body parts 2 and 3.

The purpose of making the valve body parts axially adjustable is forcontrolling the rate of flow and pressure of the fluid discharged fromthe valve, as will later be described.

The body part 2 has an inlet bore 10 coaxial with its threaded portion 4and leading to a frusto-conical seating wall 11 arranged with its smallbase disposed at the discharge end of the inlet bore 10 and with itslarge base facing toward the body part 3, so that the seating wall 11 isflared outwardly from its inlet end towardits outlet end.

Mounted within the body part 3 in coaxial, or approximately coaxial,relation with the seating wall 1 1 is a frusto-conical valve plug 12which has a peripheral wall 13 which tapers in the same direction as theseating wall 11 of the part 2, but not necessarily at the same angle. Atits larger end, the plug has a rim 14 in which notches or grooves 15 areprovided oblique to the axis of the plug so that water and liquidflowing through the valve passes in part through the notches 15 causingthe plug to rotate very slowlyabout its axis as it unseats. The plug 12is provided with a stem 16 which is coaxial, or substantially coaxialtherewith and which extends from thepl'ug toward the outlet of the part3. The stem 16 is loosely received in a passage 17 of a spider 18 whichis mounted within the part 3. The passage 17 is approximately coaxialwith the inlet passage 10 and the seating wall 11 and accommodates thestem 16 with substantial radial clearance so that the stem can shift orfloat freely to a limited extent radially as well as axially, can rockan appreciable amount transversely of its axis, and can rotate freelyabout its axis. The clearance also renders the stem and wall of thepassage 17 selfcleaning. This arrangement is such that the stem andspider cooperate to direct the plug generally toward the seating wall 11in approximate alignment therewith while allowing the plug itself tofloat slightly radially and rock slightly for adjusting itself in theproper position relative to the seating wall 11 to assure proper closingand sealing of the valve. Sealing is effected by means of an O-ring 20carried in an external annular groove 21 in the plug near the rim 14.The O-ring 20 is seated in the groove so that it is held substantiallyin fixed position axially of the plug. The ring is of such diameter andcross section that it protrudes outwardly beyond the tapered peripheralsurface of the plug sufficiently so that when the plug 12 is moved asufficient distance toward the seating wall 1 1, the O-ring engages thewall 11, centers the plug, and effects a tight seal therewith while theperipheral wall 13 of the plug is slightly radially spaced from the wall11. Thus the walls 11 and 13 do not interfere with the seating of the O-ring despite roughness or inaccuracies in their surfaces, andinaccuracies in alignment of the seating wall 11, the stem 16, the plug'12, and the wall of the passage 17 do not prevent proper sealing.

Instead, the plug finds its own proper position for effecting the seal,shifting radially and rocking, if necessary, to this end. I

A light spring 23 is disposed between the spider 18 and the large end ofthe plug 12 so as to bias the plug to the sealing position.

Preferaly, the surface of the sealing wall 11 and the peripheral surface13 of the plug 12 are coated with TEFLON or other types of plasticcoating which has a lubricating effect and is resistant to corrosion andadherence of any foreign matter thereto. Such a coating also reducesfriction and facilitates the flow through the valve. The coating assistsin assuring better seating of the plug and sealing by the O-ring. Also,particularly when-combined with the rotation of the plug due to thenotches 15, it renders the seating wall and plug surface 13self-cleaning.

in FIG. 4, when the plug is in seating position, the clearance betweenthe peripheral surface 13 of the plug and the seating wall 11 isindicated at24. This clearance may be uniformly distributed about theplug 12 or the surface 13 of the plug may engage the wall 11 slightly atone side of the plug, with the result that most of the clearance is atthe opposite side of the plug. When uniformly distributed, thisclearance is about 1/64 of an inch, depending upon the size of the plug.

it is desirable that, in the operation of the valve, the plug 12 isnever moved axially to a position in which it is totally withdrawn fromthe space defined by the seating wall 11. This is because, duringmovement toward closed position, regardless of any rocking of the valve,the tapered portion between the small end and the 0- ring will strikethe wall 11 and guide the plug into a proper position for effectivesealing by the O-ring.

In order to assure that the plug is not fully removed from this spacedefined by the wall 11, an abutment 26 is provided on the stem 16 and isin a position to engage the spider 18 to limit the movement of the plugin a direction axially away from the seating wall 11 in the openingdirection of the plug so that a substantial portion of the plug betweenthe O-ring and its smaller end is always within the axial limits of thewall 11. The abutment 26 may be in the form of a nut threadablyconnected to the stem so as to be adjustable axially thereof. Theabutment 26 is securely held in adjusted position by a jam nut 27.

The abutment 26 can be adjusted not only to limit the maximumdisplacement of the plug 12 axially toward the discharge end of thevalve, but also limit the degree of unseating of the valve and thusadjust the flow from substantially zero to maximum rated flow. Forexample, if very restricted maximum flow is desired, the abutment 26 maybe screwed away from the plug 20 so as to provide maximum opening of theplug 12'to a position in which the O-ring is barely unseated. Byscrewing the abutment 26 in the opposite direction, the plug 'may bemoved to a fully open maximum flow position,

as illustrated in FIG. 3, or to selected intermediate positions. Thus aselected rate of flow can be pre-set before the valve is assembled. Bothrate of flow and the control of pressure can be adjusted from theexterior of the valve body by manipulation of the 'parts 2 and 3 of thebody to different relatively telescoped positions axially, and lockingthem in a selected position by the jam nut 8. For example, by graspingthe parts 2 and 3 of the body and rotating them relative to each otherin one direction they can be driven to a relatively more telescopedposition in which case, while the position of the abutment 26 remains infixed position on the stem 16, maximum opening of the valve can belimited so as to permit a very restricted flow. Furthermore, by thisadjustment, the spring 23 can be compressed to different degrees, thuschanging the resistance to unseating of the plug, or to further openingof the plug when already unseated. This controls the pressure atwhichthe valve opens and also its delivery pressure.

Various combinations of theseaxial adjustments of the body parts 2 and 3and of the abutment 26 are possible, and provide a wide range ofeffective opening pressures and discharge delivery pressures.

As a result ofthis arrangement for sealing by virtue of the O-ring,without requiring a seating contact between the peripheral surface 13 ofthe plug and seating wall 11, the seating wall 11 and the surface 13 maybe formed by simple molding operations, whether in metal or plastic,because the surface of the walls 11 and the surface 13 need not be assmooth, or polished or lapped and as accurately machined and aligned aswould be necessary if the seal were to be between the walls 11 andsurface 13. The effective sealing by the O-ring is due in part to thefree floating of the plug a limited amount radially and, in part, to therelatively free rocking of the plug provided by the substantialclearance between the stem 16 and the walls of the passage 17.Consequently, the stem 16 and the spider passage 17 do not have to beprecisely machined with respect to each other, as the play allowingslightradial migration of the stem and rocking thereof is desirablerather than being a handicap.

The valve and the parts thereof may be made of plastic or metal orvarious casting compositions. Further, with the present arrangement, thegreater the back pressure the tighter the'sealing effect. Due to thetapered arrangement of the surface 13 and wall 11, there w is no dangerof the O-ring squeezing out between the plug 12 and the wall 1 1. As theback pressure increases,

the clearance is progressively decreased and the O-ring progressivelycompressed radially.

Further, the structure lends itself to a range from very small valves tovery large valves in which serious problems were heretofore presenteddue to extreme weight of the valve plug and the necessity for preciselymachined cooperating seating surfaces and heavy and precisely surfacedguiding means.

Referring next to FIG. 7, a valve similar to that heretofore describedis illustrated and comprises a body 30 having relatively telescopicthreaded parts 31 and 32. A valve plug 33 is supported in the body by adual stem, one stem 34 being provided at the inlet side of the plug andanother stem 35 being provided at the outlet side of the plug. The stem35 is provided with an abutment nut 36, corresponding to the abutment 26heretofore described. The stem 34 also is provided with an abutment nut37, and a jam nut 38, so that selected maximum opening positions of thevalve can be controlled by an adjustment of the nut 37 axially of thestem 34. A supporting spider 39 in which the stem 34 is loosely guidedis mounted in the body.

If desired, a seating spring 40 may be interposed between the nut 37 andthe spider,

By adjusting the nut 37, a total effective spring force biasing thevalve plug toward seated position, can be adjusted, whereby pressurecontrol is provided.

The plug 33 may be solid or, if desired, it may be hollow, asillustrated in FIG. 3, so that the peripheral wall of the plug,especially in the locale of the O-ring 20, can yield resilientlyslightly outwardly under extremely high pressures applied at its largeend, to assist in sealing. Such a hollow plug has a high resistance toradial collapse.

Another advantage of the hollow plug is the reduction in weight so thatthe plug is less subject to inertial forces and can seat and unseatreadily. A further advantage is that in the case of large plugsoperating with their axes horizontal, the weight of the plug, even whenguided at both ends, can adversely affect operation, especially withmetal plugs a foot or more in diameter. Consequently, it is desirablethat the plug be as light as possible to facilitate manufacturing,handling and repairs and to reduce frictional forces during operations.However, in some instances, lightness is desired combined withexceedingly high strength. For this purpose, the structure illustratedon FIGS. 8 and 9 is used. As there illustrated, a plug 42, similar tothe plug 33, having an O-ring 43, is used. The plug 42 is made lightwhile retaining the strength by making the internal structure ofcellular or honeycomb formation, as indicated at 44. This impartslightness while concurrently offering great resistance to inward radialcollapse of the plug. At the same time it does notnecessarily completelyprevent slight expansion of the plug radially.

Referring next to FIG. 10, the principles of the present invention areshown embodied in a control valve such as is used on garden hoses andthe like, and as described in my copending application for US. lettersPat., Ser. No. 723,377, fileclApr. 23, 1968 and entitled Spray Nozzle"now U.S. Pat. No. 3,632,046. As illustrated in FIG. 10, the controlvalve has a body 50 with an outlet 52 to which a spray nozzle 53 may beconnected, if desired. The valve includes a tapered plug 54 cooperatingwith an annular seating wall surface 55 whichtapers in the samedirection as the plug. An 0- ring 56 is provided in an annular groove onthe plug for effecting a seal while the peripheral wall of the plug 54is out of sealing relation to the surface 55. The plug is guided at oneend loosely by a stem 58. At the other end a stem 59 is provided andextends through a suitable passage'60 in the body 50, an O-ring 61 beingmounted in the body slidably engaging the stem 59 while preventingescape of fluid or water between the stem and the wall of the passage60. The stem 59 not only serves the function of holding the plug inapproximate alignment with its seat in various axial positions of theplug, but also extends outwardly of the body and has its outer end,indicated at 62, in engagement with a pivoted handle 63 which isoperable for opening the valve when desired. The plug 54 is biased by aspring 64 to seating position, the plug and spring being insertablethrough an opening in the upper end of the body 50. After insertion ofthe plug and spring, the opening in the upper end is closed by asuitable screw plug 65 and sealed by a suitable O-ring 66.. This reducesgreatly the number of fittings heretofore necessary in structures ofthis type.

The O-rings heretofore described are shown as the conventional oneswhich have a circular cross section. However, as illustrated in FIG. ll,O-rings such as the O-ring 68 may be used. This O-ring is of the typehaving a large concave, outwardly opening groove 69 in its outer wall,the groove terminating short of the ends so that the end margins of thering, at the axially opposite sides of the groove 69, as indicated at70, provide the sealing surfaces. An annular tension spring 71 isdisposed in the base of the groove and is normally under a tension so asto urge the ring to the contracted condition. This type of O-ring canmaintain its position axially of the plug without any tendency to rollabout its circumferential axis, while making an effective seal whichincreases as the pressure increases.

Having thus described my invention, I claim:

l. A valve comprising a hollow body having an inlet and an outlet; anannular frusto-conical seating wall in the body between theinlet andoutlet and tapering axially in one direction; 7 a plug having aperipheral annular frusto-conical wall tapering in said one directionand movable toward and away from said seating wall upon axialreciprocation of the plug toward seated and open positions,respectively; said frusto-conical walls each having an acute includedangle; aligning means for guiding the plug toward and away i from seatedposition; a spring biasing the plug toward seated position; said plughaving a circumferential groove therein; a resilient O-ring sealdisposed in said groove and constrained thereby within predeterminedvery close limits axially of said plug wall and protruding radiallytherefrom beyond the adjacent surface of said plug wall; said O-ringbeing of much less length axially than said walls and being related incross sectional size and shape to said walls so as (a) to form a tightseal for stopping flow through the body while said walls are in closelyadjacent, radially spaced, relation to each other, and (b) to constrainthe walls from seating contact throughout their extent at all timeswhile the O-ring is effecting said tight seal;

each of said frusto-conical annular walls being of sufficient lengthaxially so that a substantial length of said frusto-conical wall of theplug is disposed between the end limits of said frusto-conical seatingwall in all axial positions of the plug, and defines with said seatingwall an annular flow passage of substantial length axially in all ofsaid open positions of the plug.

2. The structure according to claim 1 wherein aligning means areprovided in the body and are connected to the plug so as to direct theplug in a path generally toward the seating wall while supporting theplug for free floating movement along said path andlimited free rockingand migrating movement transversely of said path; and said aligningmeans comprise a stern on, and coaxial with, the plug;

a guiding sleeve carried in the body and embracing the stem looselyenough so that the stem can rock appreciably transversely of its axis.

3. The structure according to claim 2 wherein said stem is on the end ofthe plug opposite from the frustoconical wall of the plug and extendsaway from the seating wall in the direction of opening of the plug;

said spring is carried on the stem;

a second aligning means is provided and includes a stem on, and coaxialwith, the plug at the opposite end of the plug and extending therefromin the closing direction of the plug;

a second guiding sleeve is carried in the body and embraces and guidesthe second stem; and

a second spring is carried on the second stern and biases the plugtoward seated position.

4. The structure according to claim 3 wherein means are provided for.adjusting the forces applied by the springs to the plug independently ofeach other.

5. The structure according to claim 3 wherein the body has two separateparts connected together for movement to different adjusted positionsaxially of the stems;

one of said stems extends into one body part and the other stem extendsinto the other body part;

the restraining means includes abutments in the body parts,respectively, each abutment being in fixed axial position in itsassociated body part; and

abutments on the stems, respectively, complementary to the abutments inthe body parts, respectively.

6. The structure according to claim 5 wherein at least one of saidcomplementary abutments is adjustable axially of its associated stem.

7. The structure according to claim 6 wherein at least the spring in onebody part is disposed between the abutment on the stem in said body partand the complementary abutment in said body part, whereby the force ofsaid last mentioned spring can be adjusted by moving the body partsaxially relative to each other.

8. The structure according to claim 1 wherein a stop is carried by thebody structure;

a complementary stop is carried by the plug structure;

said stops being operative when in engagement to arrest movement of theplug away from said seating wall at a predetermined maximum openposition of the plug;

said stop on the plug being adjustable axially to different positionsrelative to the plug for preselecting the maximum open position of theplug.

9. The structure according to claim 8 wherein the body is in twoseparate parts in coaxial relation to each other;

means operable from the exterior of the body parts connect said partsfor movement axially toward and away from each other to differentadjusted positions;

the said stop carried by the body structure is carried by one of thebody parts and is movable axially therewith to different adjustedpositions; and

the spring is connected to one of the body parts for adjusting the forceof the spring in predetermined relation to the relativeaxial position ofthe parts.

10. The structure according to claim 9 wherein the body inlet is in oneof said body parts and the body outlet is in the other of said bodyparts;

connecting means are provided on the parts, respectively, for connectingthe body in a pipe line between the terminals thereof.

ll. The structure according to claim 1 wherein said valve plug isresiliently expansible radially, at least at and adjacent the locationof the O-ring, the degree of said resiliency is less' than that of theO-ring.

l2. Thestructure according to claim 1 wherein plug rotating means areprovided on the plug and have surfaces disposed in the path of fluidflow through the body, and are shaped and arranged to be impelled by thefluid flow so as to rotate the plug about its axis.

13. The structure according to claim 1 wherein the O-ring groove andO-ring are spaced axially a substantial distance from each of the endsof said frustoconical wall of the plug. t a m a a

1. A valve comprising a hollow body having an inlet and an outlet; anannular frusto-conical seating wall in the body between the inlet andoutlet and tapering axially in one direction; a plug having a peripheralannular frusto-conical wall tapering in said one direction and movabletoward and away from said seating wall upon axial reciprocation of theplug toward seated and open positions, respectively; said frusto-conicalwalls each having an acute included angle; aligning means for guidingthe plug toward and away from seated position; a spring biasing the plugtoward seated position; said plug having a circumferential groovetherein; a resilient O-ring seal disposed in said groove and constrainedthereby within predetermined very close limits axially of said plug walland protruding radially therefrom beyond the adjacent surface of saidplug wall; said O-ring being of much less length axially than said wallsand being related in cross sectional size and shape to said walls so as(a) to form a tight seal for stopping flow through the body while saidwalls are in closely adjacent, radially spaced, relation to each other,and (b) to constrain the walls from seating contact throughout theirextent at all times while the O-ring is effecting said tight seal; eachof said frusto-conical annular walls being of sufficient length axiallyso that a substantial length of said frustoconical wall of the plug isdisposed between the end limits of said frusto-conical seating wall inall axial positions of the plug, and defines with said seating wall anannular flow passage of substantial length axially in all of said openpositions of the plug.
 2. The structure according to claim 1 whereinaligning means are provided in the body and are connected to the plug soas to direct the plug in a path generally toward the seating wall whilesupporting the plug for free floating movement along said path andlimited free rocking and migrating movement transversely of said path;and said aligning means comprise a stem on, and coaxial with, the plug;a guiding sleeve carried in the body and embracing the stem looselyenough so that the stem can rock appreciably transversely of its axis.3. The structure according to claim 2 wherein said stem is on the end ofthe plug opposite from the frusto-conical wall of the plug and extendsaway from the seating wall in the direction of opening of the plug; saidspring is carried on the stem; a second aligning means is provided andincludes a stem on, and coaxial with, the plug at the opposite end ofthe plug and extending therefrom in the closing direction of the plug; asecond guiding sleeve is carried in the body and embraces and guides thesecond stem; and a second spring is carried on the second stem andbIases the plug toward seated position.
 4. The structure according toclaim 3 wherein means are provided for adjusting the forces applied bythe springs to the plug independently of each other.
 5. The structureaccording to claim 3 wherein the body has two separate parts connectedtogether for movement to different adjusted positions axially of thestems; one of said stems extends into one body part and the other stemextends into the other body part; the restraining means includesabutments in the body parts, respectively, each abutment being in fixedaxial position in its associated body part; and abutments on the stems,respectively, complementary to the abutments in the body parts,respectively.
 6. The structure according to claim 5 wherein at least oneof said complementary abutments is adjustable axially of its associatedstem.
 7. The structure according to claim 6 wherein at least the springin one body part is disposed between the abutment on the stem in saidbody part and the complementary abutment in said body part, whereby theforce of said last mentioned spring can be adjusted by moving the bodyparts axially relative to each other.
 8. The structure according toclaim 1 wherein a stop is carried by the body structure; a complementarystop is carried by the plug structure; said stops being operative whenin engagement to arrest movement of the plug away from said seating wallat a predetermined maximum open position of the plug; said stop on theplug being adjustable axially to different positions relative to theplug for preselecting the maximum open position of the plug.
 9. Thestructure according to claim 8 wherein the body is in two separate partsin coaxial relation to each other; means operable from the exterior ofthe body parts connect said parts for movement axially toward and awayfrom each other to different adjusted positions; the said stop carriedby the body structure is carried by one of the body parts and is movableaxially therewith to different adjusted positions; and the spring isconnected to one of the body parts for adjusting the force of the springin predetermined relation to the relative axial position of the parts.10. The structure according to claim 9 wherein the body inlet is in oneof said body parts and the body outlet is in the other of said bodyparts; connecting means are provided on the parts, respectively, forconnecting the body in a pipe line between the terminals thereof. 11.The structure according to claim 1 wherein said valve plug isresiliently expansible radially, at least at and adjacent the locationof the O-ring, the degree of said resiliency is less than that of theO-ring.
 12. The structure according to claim 1 wherein plug rotatingmeans are provided on the plug and have surfaces disposed in the path offluid flow through the body, and are shaped and arranged to be impelledby the fluid flow so as to rotate the plug about its axis.
 13. Thestructure according to claim 1 wherein the O-ring groove and O-ring arespaced axially a substantial distance from each of the ends of saidfrusto-conical wall of the plug.